My fellow students and me are working on a sound and light installation for a university project. We want to create sound with the Arduino Board. But we have no direct connection with a laptop or PC, we need a wireless connection (W-LAN).With the Arduino Board itself you only get a really bad sound quality, 8-Bit and mono if I'm right...?

Now my question is, if there is a easy way to connect something like a soundcard directly to the Arduino Board. One solution could be the Wave Shield, where you can store wav files on a SD-card... Does anyone have a better solution ?

Welcome to the arduino world. imho the wave shield is one of the better/cheaper solutions.

you need to have a wifi shield to send a command to a PC to do the sound /light you want. On the PC you embed a webserver with some forms to choose sound and light and the Arduino just fills in these forms. Example code can be googled for and if it doesn't work come to the forum for assistance.